Should We Avoid Foods That Spike Our Blood Sugar?

Should We Avoid Foods That Spike Our Blood Sugar?

Wondering if you need to give up sugar, carbs, or any other food that might spike your blood sugar? The quick answer is no, but as always there is some context and nuance to delve into.

First off, let’s review what happens in our bodies when we consume carbohydrates.

When we eat carbs, our blood sugar goes up. In response, the pancreas releases insulin, a hormone that helps sugar move into our body’s cells. Insulin attaches to special spots on the outside of cells (receptors), setting off a chain reaction that relocates the glucose transporter, GLUT4, from inside the cell to within the cell membrane. This process activates GLUT4 so that it can start moving glucose from outside of the cell to inside the cells. Insulin also tells the liver to turn glucose into glycogen, which is stored in the liver and muscles for quick energy, and into triglycerides, which are stored in fat tissues for longer-term energy.

What happens in insulin resistance and type 2 diabetes? A combination of things that interfere with this system.

If blood sugar levels are high for a long time, cells change and become less responsive to insulin. These changes can include having fewer insulin receptors on cell surfaces, and weakening the reactions inside the cell that occur after insulin binds with its receptors. For example, receptors may not bind to insulin as effectively, or the GLUT4 transporter might work a little bit more slowly to bring glucose into the cell.

When cells become less sensitive to insulin, the pancreas has to release more insulin to manage high blood sugar. This condition is known as insulin resistance, where the body needs more insulin than usual to handle glucose. If this continues and the body can’t keep blood sugar levels normal, it leads to prediabetes and eventually type 2 diabetes.

This is bad but eating carbs or even the simplest of sugars doesn’t directly cause this to happen. A variety of nutrient deficiencies can interfere with this system. For example, low vitamin D levels can reduce the number of insulin receptors in cell membranes, can lower the activity of the GLUT4 glucose transporter, and can reduce beta cell health and the ability of the pancreas to secrete insulin – all of the insulin resistant things.  What’s more, a variety of nutrients are required for the system to function normally so too low levels of any one of them can contribute to the development of insulin resistance.

In addition, lifestyle factors can have an even stronger impact on insulin sensitivity than diet factors, including not getting enough sleep, living a sedentary lifestyle, and having high stress levels. For example, in a 2007 study where participants were subjected to 5 days of bed rest, they had a 67% increase in insulin secretion following a glucose challenge test (meaning two thirds more insulin was needed to regulate blood glucose levels) after the bed rest. And, this inactivity-induced insulin resistance is paired with dyslipidemia (an imbalance of lipids such as cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides), increased blood pressure, and impaired microvascular function—no wonder being inactive so dramatically increases risk of diabetes, obesity, and cardiovascular disease! In addition, sleeping less than 6 hours per night (like an estimated 40% of Americans) increases risk of type 2 diabetes by 50%. And, if we pool diabetes and impaired glucose tolerance together, that risk soars to a whopping 2.4 times!  

All this tells us that we need to take a holistic approach to metabolic health, focusing on lifestyle in addition to filling our mealtimes with a diet abundant in nutrient-dense whole foods such as leafy greens, legumes, starchy and non-starchy vegetables, and seafood for example.

Of course, if you already have insulin resistance or type 2 diabetes, you want to be intentional with how much carbohydrates you are consuming with each meal and making sure to consume them with some protein, healthy fat, and fiber to help blunt the sugar response.

But we don’t want to avoid all carbs or even all sugar since we need insulin for many functions beyond glucose metabolism. For instance, insulin supports thyroid function by activating an essential enzyme (type 2 deiodinase) that converts the thyroid prohormone T4 into the active hormone T3. Insulin increases the rate of transport of important amino acids into muscle tissue and increases muscle protein synthesis, while simultaneously reducing muscle protein breakdown. This means that insulin is really important for muscle recovery and fitness. Insulin is also important for maintaining healthy bones. It regulates bone remodeling by driving osteoblast activity, the cell type responsible for bone mineralization. Furthermore, insulin acts in the hippocampus to promote learning and memory, and to support synaptic plasticity, while reducing microglia cell activity (resident immune cells in the brain). Insulin also interacts with the endocrine system, impacting estrogen and testosterone levels.  It regulates sex hormone levels by suppressing sex-hormone binding globulin and by enhancing estrogen and testosterone production. It also interacts with cortisol, growth hormone, glucagon, and hormone neurotransmitters like dopamine, serotonin and melatonin (the sleep hormone).  

All of these systems can be negatively impacted by insulin resistance but also by eating too low of a carbohydrate diet.

Overall, it is normal for our blood sugars to increase short-term after a meal, what we want to avoid is them increasing too high and staying high for too long. However, the goal is not to control blood sugar so that it is flat and steady! 

Studies show keeping added sugars below 10% of total calories does not increase risk for metabolic health problems. And when we consider all dietary sugars (added sugars and natural ones like those found in whole fruit), the cut off is more like 25% of total calories. Bottom line, with sugar (like all dietary components) we want to keep our intake in the happy medium range.

If you’d like to hear my thoughts on whether or not we need to go low-carb, avoid all sugar or any food that could cause blood sugar spikes, check out my video.

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